Kohji (rice malt) is an essential ingredient for making Sake as it acts to convert starch into sugar. The fermentation process required for Sake production cannot take place without the inclusion of rice malt. The “Kojiki” (the oldest extant chronicle in Japan) mentions that people brewed Sake with rice malt and presented it to the emperors. This means that Sake production was already established when the “Kojiki” was written in 712.
It is believed that rice malt was imported from ancient China, but the Japanese way of producing Sake was completely different from the way it is nowadays produced in China. Flour is used as the principal ingredient for making Sake in China. After kneading it into a brick, a rhizopus mold is produced in it to produce kohji. In contrast, in Japan, steamed rice is used in the kohji-producing process. Different ingredients and techniques have thus been used in China and Japan to create Sake. Although the most commonly held theory is that Kohji originally came from China, some people believe that the technique of producing kohji using steamed rice originated in Japan. In either case, there is no doubt that the foundation of Sake manufacture was established step by step during the Nara Era (710–794). It evolved into the processes seen today, which use bacterial action, from the technique of converting starch into sugar using human saliva, known as “Kuchikami Sake” (liquor made by chewing with one’s mouth).
THE HISTORY OF SAKE
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Kohji - the most important ingredient for producing Sake -
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Rice contains no sugar. This means that it cannot ferment by itself without something else added. An action that transforms the starch into sugar is therefore needed. Rice malt is used for this transformation. In short, we can say that Kohji is a cultivated microorganism to transform starch into sugar. Aspergillus is the microorganism that enables this transformation of starch into sugar. It is mixed with steamed rice and the mixture is left in a warm place for up to 50 hours to produce kohji. “Putting rice malt to practical use” was a method for transforming rice into Sake. There is a saying from olden times that goes “Koji (rice malt) comes first, Moto (yeast mash) comes second, and Tsukuri (preparation) comes third.” This saying reflects the order of Sake production and the ingredients essential for making high-quality Sake.
There are three essential raw materials for Sake production – rice, Kohji (rice malt), and water. Here, we shall now put together basic knowledge about Kohji, which has a vital role in the production of fine Sake.